A dual layer semiconductor channel employed for vertical memory devices provides the benefit of protecting an underlying memory film, and particularly the tunneling dielectric therein, during an anisotropic etch that removes a bottom portion of the memory film to physically expose surfaces of a semiconductor substrate that includes horizontal portions of semiconductor channels. A first semiconductor channel layer is deposited prior to the anisotropic etch over the tunneling dielectric, and a second semiconductor channel layer is deposited after the anisotropic etch directly on a surface of the semiconductor substrate and on remaining vertical portions of the first semiconductor channel layer.